1. Field of the Invention
The present invention relates to a method of fabricating a composite material wing, such as a fiber-reinforced plastic, and, more specifically, to a method of fabricating a composite material wing of a box structure having closed spaces by a single high-temperature heat-setting process to shorten a molding process and to reduce assembling work.
2. Description of the Related Art
Most conventional aircraft main wings are of built-up construction. Further lightweight aircraft main wings of a composite material having a high specific strength have been developed. A composite material aircraft main wing of a box structure is assembled by joining together parts including spars, skins and ribs individually formed by a resin transfer method (RTM) or a hand lay-up method with an adhesive or fasteners in a box structure. Since a part of a fiber-reinforced plastic, i.e., composite material, is soft before being set, the part of the fiber-reinforced plastic must be kept in a desired shape by using a mandrel and the mandrel must be removed after setting the part of the fiber-reinforced plastic. Therefore, the conventional wing of a box structure can not be formed in an integral structure by molding; the wing must be provided with an opening through which a mandrel can be removed, and an individually formed member for closing the opening must be joined to the wing with fasteners or an adhesive.
Forming jigs are used in forming the parts for the aircraft main wing of a box structure including spars, skins and ribs. The forming jigs must be made of a heat-resistant material because the parts are formed at high temperatures by a heat-setting process.
When assembling a composite material aircraft main wing by an assembling method using an adhesive, the parts need to be subjected to high-temperature heat setting twice when forming the parts and when adhesively assembling the same. When assembling the aircraft main wing of a composite material by an assembling method using fasteners, the parts need to be subjected to heat setting only once. However, this method of assembling the main wing that joins together the parts with the fasteners needs assembling jigs and takes much time.
Accordingly, it is an object of the present invention to provide a method of fabricating an aircraft main wing of a composite material in a box structure having closed spaces capable of forming the main wing by a low-temperature half-setting process and a heat-setting process, of shortening a molding process and reducing assembling work.
According to a first aspect of the present invention, a method of fabricating a composite material wing includes the steps of: superposing a reinforcing textile sheet on a mandrel; closely enclosing the reinforcing textile sheet superposed on the mandrel in a closed jig; introducing a thermosetting resin into the closed jig to impregnate the reinforcing textile sheet with the thermosetting resin; making the thermosetting resin impregnated into the superposed reinforcing textile sheet half-set to form a half-set composite material wing component member; taking the half-set composite material wing component member and the mandrel out of the jig; removing the mandrel from the half-set composite material wing component member; bonding the half-set composite material wing component member and an other wing component member with an adhesive to form an assembly; and heat-setting the assembly to complete a composite material wing.
Preferably, the other wing component member is a composite material wing component member formed by impregnating a reinforcing textile sheet with a thermosetting resin. Preferably, the composite material wing is a box structure having a closed space. Preferably, each of the wing component members includes at least one of a front spar, a rear spar, a plurality of ribs extended between the front spar and the rear spar, an upper skin overlying the ribs, and a lower skin underlying the ribs. Preferably, at least one of the wing component members is an integral member formed by integrally combining at least two of the front spar, the rear spar, the ribs, the upper skin and the lower skin.
According to a second aspect of the present invention, a method of fabricating a composite material wing including a front spar, a rear spar, a plurality of ribs extended between the front and the rear spar, an upper skin overlying the ribs and a lower skin underlying the ribs includes the steps of: superposing a plurality of reinforcing textile sheets for the rear spar, the ribs, the upper skin and the lower skin on a mandrel corresponding to a wing structure; closely enclosing the reinforcing textile sheets superposed on the mandrel in a closed jig; impregnating the reinforcing textile sheets with a thermosetting resin by introducing the thermosetting resin into the closed jig; making the thermosetting resin impregnated into the superposed reinforcing textile sheets half-set to form a half-set composite material wing component member; taking the half-set composite material wing component member and the mandrel out of the closed jig; removing the mandrel from the half-set composite material wing component member integrally including the rear spar, the ribs, the upper skin and the lower skin; bonding the half-set composite material wing component member and a wing component member corresponding to a front spar with an adhesive to form an assembly; and heat-setting the assembly to complete a composite material wing.
Preferably, the wing component member corresponding to the front spar is a half-set composite material member formed by impregnating a reinforcing textile sheet with a thermosetting resin.
The reinforcing textile sheets superposed on the mandrels are sealed in the closed jig, the superposed reinforcing textile sheets are impregnated with the thermosetting resin, the thermosetting resin impregnated into the superposed reinforcing textile sheets is half-set to form the half-set component members or the composite component member, the mandrels are removed from the half-set component members or the composite component member, the half-set component members are assembled and adhesively bonded together with the adhesive to form a composite structure and the composite structure is subjected to the high-temperature setting process to set the thermosetting resin. Thus, the thermosetting resin and the adhesive can be simultaneously heated and hence only a single high-temperature setting process is necessary for forming the composite material wing of a box structure having closed spaces.